The objective of the research included in this proposal is to gain an understanding of the hormonally mediated molecular processor whereby epididymal function, sperm maturation, and sperm survival are mediated. To accomplish this objective we plan to: a) continue our studies on the interaction of androgens with their respective receptors in the cytosol and nuclei of the epididymis, b) determine if any interrelationship exists between the androgen and estrogen receptors in the epididymis, c) examine developmental changes that may occur in the type of receptor (i.e., estrogen and androgen), the distribution of receptor, and the quantity of receptor present in the epididymis, d) continue our studies on the metabolism of steroids by the epididymis and the compartmental distribution of metabolites. These studies will be conducted in adult animals and in immature animals during development, e) develop nuclear exchange assays to monitor nuclear binding of androgen and estrogens by the epididymis, f) continue our studies on changes in ABP concentration in the epididymis during development and on attempts to correlate these changes with morphological changes in the testis and epididymis, g) continue our studies on the role of testicular fluid on the differentiation of the caput epididymidis. Information regarding the hormonally mediated molecular events that regulate epididymal function, sperm maturation, and sperm survival should provide insights to methods for manipulating these processes, thus leading to the development of male contraceptives and to methods for alleviating infertility problems arising from epididymal dysfunction.